The present invention relates to a method and apparatus for producing high temperature water in an absorption chiller-heater, and more particularly to a method and apparatus for producing high temperature water without raising the temperature of the solution (absorption solution).
Hitherto an absorption chiller-heater using, for example, lithium bromide as an absorbent and water as a refrigerant is generally known.
A conventional absorption chiller-heater is composed, for example, as shown in FIG. 1. Numeral 10 denotes an upper low temperature shell composed of a low temperature generator 12 and a condenser 14. A refrigerant sump 16 is disposed in the lower part in the condenser 14. Numeral 18 denotes a lower low temperature shell composed of an evaporator 20 and an absorber 22. Numeral 24 denotes a high temperature generator composed of a combustion chamber 26, a heat recovery unit 28, a vapor-liquid separator 30, an exhaust pipe 32, and a combustion unit 34. Other constituent components include, among others, a low temperature heat exchanger 36 and a high temperature heat exchanger 38.
The weak solution in a liuqid sump 40 in the lower part in the absorber 22 is sent by a low temperature solution pump 42 into the low temperature generator 12 through a solution discharge pipe 44, a low temperature heat exchanger 36 and a pipe 46. This weak solution is heated by the high temperature refrigerant vapor flowing in through a pipe 48, and is concentrated to a intermediate concentrated solution.
This intermediate concentrated solution is divided in two portions. One of the two portions is sent into the high temperature generator 24 by the high temperature solution pump 50 through pipes 52, 54, high temperature heat exchanger 38 and a pipe 56. The intermediate concentrated solution is heated by the combustion unit 34, goes up the heat recovery unit 28, enters the vapor-liquid separator 30 to be separated into a refrigerant vapor and a strong solution. The strong solution passes through the strong solution pipe 58 and high temperature heat exchanger 38 due to a pressure difference between the internal pressure of about 650 mmHg in the high temperature generator 24 and the internal pressure of about 6 mmHg in the lower low temperature shell 18, and is mixed with the intermediate concentrated solution (the other portion of the divided two) from the pipe 60 divided previously to form a mixed concentrated solution, which enters the low temperature heat exchanger 36, passes through the solution feed pipe 62, and is sprayed over the heat exchanger tubes 23 of the absorber 22 by the spray means (spray device) 64, thereby completing circulation and returning to the solution sump 40.
On the other hand, the refrigerant vapor separated in the vapor-liquid separator 30 enters the low temperature generator 12 through a pipe 48, heats the solution in it, is condensed and liquefied, and is fed into the condenser 14 through a pipe 66. In the low temperature generator 12, the refrigerant vapor generated at the time of concentration of the weak solution into intermediate concentrated solution enters the condenser 14 through the upper passage, and is condensed to be a liquid refrigerant. The condensed refrigerant water enters the evaporator 20 through a pipe 68, and is accumulated in the lower sump 70. The refrigerant water is sprayed over the heat exchanger tubes 21 of the evaporator 20 from refrigerant spray means (spray device) 78 from pipes 74, 76 by a refrigerant pump 72. Along the pipe 76, an orifice 77 is installed for metering the refrigerant water. Or, instead of the orifice 77, a valve may be installed.
Chilled water presented for cooling enters the evaporator 20 through a pipe 80, and is cooled by the latent heat of evaporation of the sprayed refrigerant, and flows out through a pipe 82. The cooling water flows out through pipes 84, 86, 88, and draws absorption heat in the absorber 22 and of the condensation heat in the condenser 14 out of the system.
By opening a cooling/heating changeover valve 90 and without flow of cooling water to the pipe 84, hot water may be obtained from the pipe 82.
As described above, in the conventional absorption chiller-heater, when producing hot water from the evaporator 20, the warm water in the heat exchanger tubes 21 in the evaporator 20 is heated by the refrigerant vapor flowing into the evaporator 20 through the cooling/heating changeover valve 90.
The solution is sprayed over the heat exchanger tubes 23 of the absorber 22, and since heat is not taken out from the absorber 22 (when producing hot water, cooling water does not flow through the heat exchanger tubes 23 of the absorber), the solution is not cooled and flows into the low temperature solution pump 42.
Accordingly, when producing high temperature water, the solution temperature becomes too high, and the heat resisting temperature of the solution pump 42 must be raised. It is, however, difficult to raise the heat resisting temperature of the solution pump 42 more than the present level.
FIG. 2 is a Duhring diagram of water and lithium bromide. As clear from FIG. 2, the solution temperature is higher than the saturated steam temperature.